Refrigerant drier

ABSTRACT

A refrigerant receiver-drier comprising a metallic cartridge or cylinder having therein a desiccant-containing bag made of fabric and through which liquid refrigerant may flow. One portion of the bag occupies an end of the tank sealed by the welding of a cap thereon during manufacture of the receiver-drier. The bag and its contents are protected against the heat of such a welding operation by a sheet of metal foil secured to the bag and forming a heat shield.

United States Patent 1191 Appl. No.: 241,736

US. Cl. 55/387 Bidiwala 1 Sept. 4, 1973 [54] REFRIGERANT DRIER 2,770,31711/1956 Bottum 210/282 [75] Inventor: Bash S, Bidiwala, Richmond, Ind. IOTHER PUBLICATIONS [73] Assignee. PhilcmFM-d Corporation WestinghouseEngineer, July, 1954, pp. 147-151.

Philadelphia, Pa. Primary ExaminerChar1es N. Hart [22] Fled: 1972Att0rneyRobert D. Sanborn et a1.

[57] ABSTRACT A refrigerant receiver-drier comprising a metalliccartridge or cylinder having therein a desiccant-containing bag made offabric and through which liquid refrigerant may flow. One portion of thebag occupies an end of the tank sealed by the welding of a cap thereonduring manufacture of the receiver-drier. The bag and its contents areprotected against the heat of such a welding operation by a sheet ofmetal foil secured to the bag and forming a heat shield.

3 Claims, 4 Drawing Figures REFRIGERANT DRIER BACKGROUND OF THEINVENTION Refrigerating systems, particularly automotive airconditioning systems frequently utilize in their drier assembliesdesiccant bags of fabric, for example woven wool or polypropylene felt.Such bags are subject to a difficulty in that the bags may becomescorched during a final drier assembly operation in which a cap iswelded to one end of the cylindrical cartridge which I contains the bag.Intense heat is generated during the welding process and there may besuch deterioration of the bag as to cause failure of the direr duringsubse quent use.

Attempts have been made to overcome this difficulty by various means,including the provision of relatively heavy mesh screens, for examplescreens of Monel metal, which are inherently expensive and alsocomplicate the assembly operation. In some cases it has even beenthought necessary to avoid the use of inexpensive fabric bags, and toemploy a bag comprising Monel screening. As will be appreciated, thesepreviously known expedients have not been fully satisfactory,principally because of the expense and complications which they entail.

SUMMARY OF THE INVENTION It is a general objective of this invention toprovide a receiver-drier which overcomes these difficulties in verysimple manner by the provision of a desiccant bag which is preferablyfabricated of woven wool through which refrigerant readily flows, and byproviding a thin, inexpensive, shield secured to the bag at that endthereof which is subjected to the heat of the welding operation. Inachievement of this general objective I provide a sheet of metal foil,for example aluminum foil, folded over one end of the bag and fastenedthereto. It is a feature of the invention that the foil is appliedduring the stitching operation in which the desiccant is sealed withinthe bag. Experience has shown that this simple solution to a longstanding problem adds only about one cent, or less, to the cost of thebag.

In final assembly of the receiver-drier, the bag is inserted into thetubular metal cylinder with the foil facing the open end of thecylinder. The cap is then welded onto the open end of the cylinder, andthe foil shields the bag against overheating which would otherwise occurduring the welding operation, particularly if the bag were close to orin contact with the cap during welding.

The objectives and advantages of the invention will be more fullyunderstood from a consideration of the following description taken inlight of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional viewtaken through a receiver-drier assembly embodying the invention, theassembly being shown diagrammatically as associated with the elements ofa refrigerating system;

FIG. 2 is a cross-sectional view of the desiccantcontaining bag, takentransverse the direction of stitching;

FIG. 3 is a partially sectional view of a receiver-drier of the kindshown in FIG. 1, and illustrating the apparatus on a smaller scale,during a step in the assembly thereof; and

FIG. 4 is a fragmentary view of the receiver-drier of FIG. 3 andillustrating the welding operation.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT With more detailedreference to the drawing and first to FIG. 1 thereof, there are shownthe essential elements of a system, adapted to be used in an automotiveair conditioner. This system includes, in series circuit, 7

a refrigerant drier embodying the features of my invention. Asillustrated, the drier serves also as a refrigerant receiver. However itwill be understood that the principles of the invention are equallyapplicable to a simple through-flow drier. The illustrated systmeincludes a motor compressor 10, a condenser 11, a restrictor l2preferably an expansion valve device an evaporator l3 and means,including a pair of-fans l4 and 15 for moving air in heat exchangerelation with the condenser and evaporator.

A receiver-drier 16 embodying the invention is inter posed between thecondenser 14 and the expansion device 12, and comprises afluid-impervious metallic cylinder 17 having upper and lower endcaps 18and 18a, respectively. The lower cap is apertured at 19 and 20 toprovide ports within which are received, in fluid tight relation, arefrigerant inlet conduit 21 and an outlet conduit 22, which latter isprovided with a looped and downwardly turned portion 23 capped with afilter screen 24. Because of the relatively high pressure at which sucha system operates and in accordance with known practice, the cylinder,its end caps, and its conduits would normally be fabricated of steel.

There is provided in an upper portion of the cylinder a bag 25containing a suitable desiccant which may, for example, comprise anactive crystalline zeolitic molecular sieve ofa type now well known inthe art. The desiccant takes the form of a great number of smallindividual particles or beads, some of which are shown in the drawingand have been designated by the reference numeral 26 applied to FIG. 2.It should be understood that, in practice, the bag would besubstantially entirely filled with such beads. I

It is an important feature of the invention that the bag is of fabricmaterial, for example woven wool, and that it includes along its upperedge, as shown to best advantage in FIG. 2, a sheet of aluminum foil 27stitched along its mid-portion, as at 28, to the end of the bag andincluding portions which straddle the bag end and extend a shortdistance along the lateral portions of the bag, as shown at 29 and 29a.It is preferable that the stitching be sufficiently tight to ensure thatthe thread becomes somewhat recessed in the surface of the foil. In thisway the stitching is protected from the heat of the welding.

With particular reference to FIG. 3, it will be seen that in thesubassembly fabrication of the receiverdrier, the cap 18a through whichthe conduits pass is first secured to one end of the cylindrical tank17. Thereafter the desiccant bag is inserted into the open opposite endof the cylinder, the right hand end as it is viewed in FIG. 3, with itsfoil-bearing portion facing the open end. The end cap 18 is then fittedover the adjacent open end of the tank 17 and welded in the manner shownmore or less diagrammatically at 30 in FIG. 4. During such welding, thevery considerable heat generated during the operation, and radiatedtoward the bag 25, is prevented from damaging the bag by the action ofthe interposed foil sheet 27 which shields the material of the bag fromthe applied heat As brought out above, this invention enables use of theinexpensive and desirable fabric bag, since it provides the requisitethermal protection at a cost which is a small fraction of that involvedin use of the previous metallic heat shields. As will be appreciated thefoil is easily applied to the bag during the usual process of bagstitching.

I claim:

1. A refrigerant drier, comprising: a fluid-impervious,pressure-resistant metallic cartridge having means for ingress ofrefrigerant thereto and egress of refrigerant therefrom; cover meansadapted to be secured to the cartridge by a welding operation; adesiccantcontaining bag disposed within said cartridge and made of afabric material of a type which can be deleteriously affected by theapplication of heat thereto during the welding operation; and means forprotecting said bag against excessive heating during welding, said meanscomprising a thin sheet of metallic foil material fastened to the bagand covering that portion of the bag which would be subject to the heatof welding.

2. A drier in accordance with claim 1, and further characterized in thatsaid sheet comprises aluminum foil.

3. A drier in accordance with claim 1 and further characterized in thatsaid bag is stitched along one end thereof to retain the desiccanttherein, and said sheet of foilis folded over said end of the bag andsecured thereto by the stitches which seal the bag.

1. A refrigerant drier, comprising: a fluid-impervious,pressure-resistant metallic cartridge having means for ingress ofrefrigerant thereto and egress of refrigerant therefrom; cover meansadapted to be secured to the cartridge by a welding operation; adesiccant-containing bag disposed within said cartridge and made of afabric material of a type which can be deleteriously affected by theapplication of heat thereto during the welding operation; and means forprotecting said bag against excessive heating during welding, said meanscomprising a thin sheet of metallic foil material fastened to the bagand covering that portion of the bag which would be subject to the heatof welding.
 2. A drier in accordance with claim 1, and furthercharacterized in that said sheet comprises aluminum foil.
 3. A drier inaccordance with claim 1 and further characterized in that said bag isstitched along one end thereof to retain the desiccant therein, and saidsheet of foil is folded over said end of the bag and secured thereto bythe stitches which seal the bag.